A safe way to deliver drugs to the placenta

Researchers from the University of Manchester have devised a method to selectively deliver drugs to a pregnant woman’s placenta without harming the foetus.

This development could help prevent some premature births and treat conditions such as pre-eclampsia.

The scientists demonstrated that two peptides originally used to target tumours selectively will perform the same function on a placenta, delivering drugs which improve placental function and benefit the growing baby without causing it harm.

Many pregnancy complications are caused by the placenta not growing or functioning correctly. But currently there are no drugs that can be used to treat pregnancy complications, such as pre-eclampsia or foetal growth restriction, which affect more than ten percent of pregnant women. Instead doctors have to induce early delivery of the baby.  Premature babies are at increased risk of developing infections and cerebral palsy and throughout their lives have an increased risk of heart disease and diabetes. 

The Manchester research has the potential to avoid these problems by treating the baby inside the mother and avoiding induced labour. Dr Lynda Harris, the lead researcher explained:  “Placentas behave like well-controlled tumours. They grow quickly, produce growth hormones and evade the immune system.

“A lot of cancer research focuses on finding ways of delivering drugs to kill the tumour without affecting the rest of the body.  We had the idea that if we could selectively target the placenta in the same way, we could deliver other drugs which help improve placental function and therefore treat pregnancy complications.”

Growth hormone delivered to placentas in mice

As a result the researchers have demonstrated that in mice a growth hormone can be delivered to placentas, which has no effect on normal-sized foetuses, but helps undersized ones to grow, proving that there is potential for this method to be used in humans.

There were no signs that these drugs built up in the mouse’s organs, instead passing out of the body, and there were no drugs found in the mouse foetuses. The researchers acknowledge that there may be harmful effects in mothers who have undiagnosed cancers, because the drugs will also target their tumours, but they suggest a screening programme would overcome these difficulties.

Dr Harris added: “By developing this platform we have opened up the possibility of any number of new drugs which can be adapted and then used safely to treat common and serious pregnancy complications.”